From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 761F1C4320E for ; Thu, 26 Aug 2021 17:25:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 544BF6103E for ; Thu, 26 Aug 2021 17:25:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243191AbhHZR0S (ORCPT ); Thu, 26 Aug 2021 13:26:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44598 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232775AbhHZR0Q (ORCPT ); Thu, 26 Aug 2021 13:26:16 -0400 Received: from mail-pg1-x535.google.com (mail-pg1-x535.google.com [IPv6:2607:f8b0:4864:20::535]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 789F0C0613C1; Thu, 26 Aug 2021 10:25:28 -0700 (PDT) Received: by mail-pg1-x535.google.com with SMTP id k24so3635333pgh.8; Thu, 26 Aug 2021 10:25:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=wg3NGSKG8aeY7CfUKjajWr4BQ6jE7IKLYam6kXWpQR4=; b=FatKQJFGvF/uj4c0Nq7U98B9Wxi4EGgW/sF5kqboMN0PeaRo4s0JRHucj7JtTUJziS CEyuGxH/MDGiBkM8ahWO1ogWn/STms5ZQtaBM1ux/7Knf2VDDuICgA+frGaQgoyTdlAl MMuZuPWQw5Hu81El1wEZCOGc66b3/dRY5veu07iWn+9DHz7i42pEGCu5m66ZJHkgzoE2 vsOpCTUTrDCNQlUnCXishzRWxHnU9G89l0IDTrEnadjFvl6GcrkvHnGdeUuaqPDzN3LY owiA4Hhm5e/61zLicZIProXx/hS7Tg55CE+iNcSBbnK/wH2Fol6jBvvGmPHoxUu+gyd4 fGoA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition :content-transfer-encoding:in-reply-to; bh=wg3NGSKG8aeY7CfUKjajWr4BQ6jE7IKLYam6kXWpQR4=; b=GyTAOSwbCyX1RzytElh3EgNOxVHssaZdfTwUZNzqINU/iL439nHcCGotqf3b3eIiLd 3TDrMB85ju6Ch/jWJb7DBdRXNvrXC3wCSDJUJ29EzffQAjAfpybmei+umhthyPfe/2E2 4A86MXItIaNPljIKYCFyg9ajkboRjijB6s3CPk7AZLKkn0tGQ6swzLdJ1CCZJUFt4Nq/ XUDYd9vA4o5JPP137WHvKpc9HXPTWDj0CgBP+M35WZ5jdEqHziZEJLCRvcm2PbYg6qRX cY05uLlmmHqdwb1EQAbNbbWJwWN/s/AfbXpdQNjdazxTwSvCqNEvNrkUARzwS1fyg3Os G03g== X-Gm-Message-State: AOAM533X7VAbAS0ExqbRpAOgUsKMJ9cW+MWarx5k5y4NkrrSIIJCexKz wnzsQILtwKkdPeQVMDkUA/w= X-Google-Smtp-Source: ABdhPJxoLQ2Vjm9jEu975SKkK2f6C/Bx7IXPRMdhI++8Dm9G1SmRWFfX0y/Mh8AX3aboTF+uItwGPg== X-Received: by 2002:a65:6487:: with SMTP id e7mr4208082pgv.27.1629998727774; Thu, 26 Aug 2021 10:25:27 -0700 (PDT) Received: from localhost ([2620:10d:c090:400::5:a096]) by smtp.gmail.com with ESMTPSA id p3sm9547728pjt.0.2021.08.26.10.25.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Aug 2021 10:25:27 -0700 (PDT) Sender: Tejun Heo Date: Thu, 26 Aug 2021 07:25:24 -1000 From: Tejun Heo To: Michal =?iso-8859-1?Q?Koutn=FD?= Cc: Paolo Valente , Jens Axboe , linux-block , Jan Kara , cgroups@vger.kernel.org Subject: Re: BFQ cgroup weights range Message-ID: References: <20210824105626.GA11367@blackbody.suse.cz> <20210826131212.GE4520@blackbody.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210826131212.GE4520@blackbody.suse.cz> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Aug 26, 2021 at 03:12:12PM +0200, Michal Koutný wrote: > On Tue, Aug 24, 2021 at 02:51:47PM +0200, Paolo Valente wrote: > > BFQ inherited these constants when we forked it from CFQ. I'm ok with > > increasing max weight to 10000. I only wonder whether this would > > break some configuration, as the currently maximum weight would not be > > the maximum weight any longer. > > Thanks for the reply. Let me form the idea as a patch (and commit > message) and discuss based on that if needed (+ccrosspost into cgroups > ML). > > -- >8 -- > From: Michal Koutný > Subject: [PATCH] block, bfq: Accept symmetric weight adjustments > > The allowed range for BFQ weights is currently 1..1000 with 100 being > the default. There is no apparent reason to not accept weight > adjustments of same ratio on both sides of the default. This change > makes the attribute domain consistent with other cgroup (v2) knobs with > the weight semantics. > > This extension of the range does not restrict existing configurations > (quite the opposite). This may affect setups where weights >1000 were > attempted to be set but failed with the default 100. Such cgroups would > attain their intended weight now. This is a changed behavior but it > rectifies the situation (similar intention to the commit 69d7fde5909b > ("blkcg: use CGROUP_WEIGHT_* scale for io.weight on the unified > hierarchy") for CFQ formerly (and v2 only)). > > Additionally, the changed range does not imply all IO workloads can be > really controlled to achieve the widest possible ratio 1:10^4. > > Signed-off-by: Michal Koutný Looks fine to me. Acked-by: Tejun Heo Thanks. -- tejun